1. Field of the Invention
The present invention relates generally to motor vehicles, such as passenger cars and light trucks. More particularly, the present invention relates generally to a multi-component front end for a motor vehicle, which advances the methods by which motor vehicles are assembled.
2. Description of Related Art
Currently, the front ends of most motor vehicles are built into the vehicle body one piece or component at a time. The installation of literally hundreds of different components in the motor vehicle front end requires the manufacturer to maintain lengthy, complex, and costly assembly lines as well as extensive tooling and fixtures. This complexity is due not only to the high number of parts involved, but also the assembly methods currently used in the automotive industry and the amount of on-line adjusting and repair that is often needed to correct assembly defects. Additionally, the well-known assembly line process is highly labor intensive, again due mainly to the high number of parts and assembly methods currently used in the automotive industry.
Typically, once a painted vehicle body comes to the finish assembly line, hundreds of individual components are assembled to the vehicle body. The numerous individual components are used to complete the suspension system, steering and braking system, power train, cooling system, electrical system, etc. As stated, the individual components comprising these systems are typically added to the vehicle body one-by-one or in small subgroups to finish the assembly of the motor vehicle.
The large number of components required to assemble a motor vehicle requires the assembly line to be extremely long and requires many people to accomplish numerous discreet tasks along the assembly line. This makes the process of motor vehicle assembly unnecessarily slow and complicated and adversely affects the quality and reliability of the motor vehicle when it is completed. Additionally, the confined space within which the workers operate makes on-line service and repair tasks difficult and even dangerous. The overall complexity of the current system for assembling motor vehicles is unnecessarily slow and expensive and there is considerable room for improvement.
The present invention applies the general concept of using modules or assemblies in the manufacturing of motor vehicles. The concepts and embodiments disclosed hereinafter may be applied to other industries that utilize the long-standing assembly line technique for producing finished products, such as the aircraft, agricultural machinery, truck manufacturing, and mining vehicle industries. Generally, the present invention is a motor vehicle comprising a vehicle body having a pre-assembled, modular front end. The modular front end is comprised of several sub-modules or sub-assemblies, as discussed hereinafter.
The modular front end is based on the concept of xe2x80x9cfunctionally decouplingxe2x80x9d the several sub-modules or sub-assemblies from each other. In front end assembly techniques currently practiced in the art, the various elements or components of the front end are substantially interconnected or related. In contrast, the modular front end of the present invention has the various sub-assemblies comprising the front end substantially functionally isolated from one another. The separate functions of the sub-assemblies, which will be discussed hereinafter, are substantially independent from one another allowing any one sub-module or sub-assembly to be individually replaced without affecting the other sub-modules or sub-assemblies. This allows the sub-modules or sub-assemblies to be comprised of smaller and lighter individual components or parts, which is not easily possible in the xe2x80x9cinterrelatedxe2x80x9d front end structures generally found in the prior art. The use of separate and distinct sub-modules or sub-assemblies in the modular front end allows the overall size of the modular front end to be reduced because the sub-assemblies may be compact tightly within the modular front end. The smaller front end made possible by the modular front end of the present invention improves the overall driving and handling characteristics of the motor vehicle. For example, the smaller front end is lower in profile than those currently known in the art, which improves the driver""s view of the road and aids the driver in performing routine vehicle operations such as parking, turning, etc.
Generally, the modular front end comprises a bulkhead having a plurality of preferably integrally formed attachment mounts, a drive train assembly attached to the bulkhead at the attachment mounts, a crash energy absorption assembly attached to the bulkhead at the attachment mounts and, further, an apron assembly attached to the bulkhead assembly at the attachment mounts. The apron assembly may be at least partially supported in the vertical direction by the crash energy absorption assembly. The drive train assembly, crash energy absorption assembly, and apron assembly are each preferably attached mechanically to the bulkhead.
The bulkhead is preferably a cast bulkhead comprising a plurality of integrally formed attachment mounts. The bulkhead may be cast from aluminum alloy as a unitary body. The bulkhead may also be comprised of a plurality of individually cast components. The bulkhead may be provided as part of a bulkhead assembly. The bulkhead assembly may comprise a cast bulkhead defining a plurality of integrally formed attachment mounts and at least one structural member of the motor vehicle attached to the bulkhead. The bulkhead assembly may further include one or more electrical components attached to the bulkhead.
The bulkhead may define at least one hollow cavity formed therein for increasing strength and rigidity of the bulkhead. The at least one hollow cavity may be filled with a cast-in-place core, preferably an aluminum foam core. The hollow cavity may also be filled with polymeric foam. The at least one structural member may comprise a pair of door hinge pillars attached to attachment mounts located at opposite ends of the bulkhead. The at least one structural member may also comprise a pair of rocker panels attached to a bottom end of the bulkhead opposite the door hinge pillars. Additionally, the at least one structural member may comprise a pair of windshield support pillars attached to a top end of the bulkhead. The at least one structural member may further comprise a windshield cross member attached to the top end of the bulkhead between the windshield support pillars.
The bulkhead may comprise a first side for facing an engine compartment of the motor vehicle and a second side for facing a passenger compartment of the motor vehicle. A pair of hood hinges, which may each include a hood lift assist mechanism, may be attached to attachment mounts located on the first side of the bulkhead for supporting a hood of the motor vehicle. The electrical component(s) is preferably attached to the first side of the bulkhead, but may be attached to the second side facing the passenger compartment. The electrical component(s) may include, for example, a windshield wiper motor and/or an electrical junction box.
The drive train assembly generally comprises a drive train support and a power train assembly attached to the drive train support. The drive train support comprises a pair of elongated support members that are configured for attachment, preferably by mechanical means, to a bulkhead of the motor vehicle. By mechanical attachment or means, it is meant that mechanical fasteners, such as nuts and bolts, rivets, and the like are preferably used to attach the various elements described in this disclosure, and may include rubber isolation mounts (i.e., bushings), where necessary, to minimize vibration between elements. The drive train support further comprises a cross member interconnecting the support members. The support members are further configured to support the power train assembly such that the power train assembly is cantilevered from the support members and bulkhead forward of the cross member.
The support members and cross member may be made of aluminum alloy. The support members may be cast aluminum alloy support members. The cross member may be an extruded aluminum alloy cross member. The support members each comprise a top end and a bottom end. The cross member preferably connects the top ends of the support members. The cross member may be connected mechanically to the support members.
In the modular front end, the power train assembly is attached to the support members such that the power train assembly is cantilevered from the support members and bulkhead forward of the cross member. The support members may be attached mechanically to the bulkhead. The mechanical attachment may comprise at least one isolation mount for dampening vibration of the power train assembly. The power train assembly may comprise an engine and transmission of the motor vehicle. The engine may be mechanically attached to the drive train support and comprise at least one isolation mount for dampening vibration of the engine. The transmission may be mechanically attached to the drive train support and comprise at least one isolation mount for dampening vibration of the transmission. The drive train assembly may further comprise a steering gear of the motor vehicle attached to the bottom ends of the support members and interconnecting the bottom ends of the support members. Further, the drive train assembly may comprise a brake and suspension assembly for each front wheel of the motor vehicle. The brake and suspension assemblies are attached to the support members, respectively, and preferably the lower ends of the support members. The brake and suspension assemblies may each comprise a control arm connected to the respective support members, preferably mechanically.
The crash energy absorption assembly generally comprises an elongated bumper beam, a pair brackets attached to the bumper beam, and a pair of tubes supported by the brackets. The tubes each have a first end and a second end. The first ends of the tubes are supported by the brackets. The second ends of the tubes may be attached to the bulkhead at the attachment mounts. A crosstie may interconnect the brackets. The bumper beam, brackets, and tubes may be made of aluminum alloy.
The bumper beam may define a substantially open cross section, which may be at least partially, but preferably completely, filled with polymeric foam. The bumper beam may define a substantially xcexa3-shaped cross section. The substantially xcexa3-shaped cross section may comprise a rear wall connected to substantially parallel top and bottom walls. The brackets may be attached to the bumper beam opposite the rear wall.
The tubes may be at least partially filled with polymeric foam. The tubes may comprise a tube with a cross-sectional profile selected from the group consisting of a circle, a square, an oval, a rectangle, a hexagon, and a combination thereof. The tubes may have different cross-sectional profiles. The brackets are preferably attached mechanically to the bumper beam. The brackets may define sockets configured to receive the first ends of the tubes. The tubes may be secured mechanically in the sockets. The bumper beam may define an overall curved shape. In the modular front end, the second ends of the tubes are attached to the bulkhead at the attachment mounts. The brackets may be taper and flare brackets, which absorb impact energy using the taper and flare principle known in the art. Alternatively, the brackets may be conventional brackets and the tubes may be crush tubes for absorbing crash energy during a collision.
The apron assembly generally comprises an apron and, preferably, at least one engine accessory of the motor vehicle attached to the apron. The apron generally comprises a substantially C-shaped, unitary apron member having a depending front portion and a substantially C-shaped apron rail attached to a top end of the apron member. The apron member defines at least one integrally formed accessory attachment mount for mounting the at least one engine accessory of the motor vehicle. The apron rail is attached to the top end of the apron member and is configured for attachment to the bulkhead. Preferably, the ends of the apron rail are attached to the bulkhead. The apron rail may be configured for mechanical attachment to the bulkhead. The apron rail is preferably attached mechanically to the apron member. The apron member is preferably formed of molded plastic material and the apron rail is preferably made of aluminum alloy. The apron rail may be a hydro-formed tube defining differing cross-sectional areas along its length, which provide mounting locations for various front end components of the motor vehicle such as the vehicle fenders. The at least one accessory attachment mount may comprise a plurality of openings defined in the front portion of the apron member.
The at least one engine accessory may be a radiator and cooling fan assembly and the accessory attachment mount may be an opening defined in the front portion of the apron member. The radiator and cooling fan is supported in the opening. The at least one engine accessory may be an air conditioning condenser and the attachment mount may be a second opening defined in the front portion of the apron member. The air conditioning condenser is supported in the second opening. Additionally, the at least one engine accessory may be a transmission oil cooler and the accessory attachment mount may be a third opening defined in the front portion of the apron member. The transmission oil cooler is supported in the third opening. Further, the at least one engine accessory may be a battery and the accessory attachment mount may be an integrally formed battery hold-down. The battery is supported in the battery hold down. The apron assembly may further comprise fenders attached to the apron rail and/or headlights attached to the front portion of the apron member. Other possible engine accessories include fluid reservoirs for the radiator and cooling assembly, windshield wiper fluid etc.
The present invention is also a method of assembling a modular front end for a motor vehicle. The method comprises the steps of providing a bulkhead having a plurality of attachment mounts; attaching a drive train assembly to the bulkhead at the attachment mounts; attaching a crash energy absorption assembly to the bulkhead at the attachment mounts; and attaching an apron assembly to the bulkhead at the attachment mounts. The bulkhead may be pre-attached to the vehicle body and the various assemblies identified hereinabove assembled to the pre-attached bulkhead. Thus, the step of providing the bulkhead includes both a separate, stand alone bulkhead that is to be attached to a vehicle body, and a bulkhead that is pre-attached to a vehicle body.
The method may further comprise the step of casting the bulkhead as a unitary bulkhead. The attachment mounts are preferably formed integrally with the unitary bulkhead. The bulkhead may be cast from aluminum alloy. The method may further comprise the step of attaching at least one structural member of the motor vehicle to the bulkhead.
The bulkhead may comprise a first side for facing an engine compartment of the motor vehicle and a second side for facing a passenger compartment of the motor vehicle. The method may comprise the step of attaching at least one electrical component of the motor vehicle to the first side of the bulkhead. The drive train assembly, crash energy absorption assembly, and apron assembly may be attached mechanically to the attachment mounts located on the first side of the bulkhead.
The drive train assembly may comprise a drive train support and a power train assembly. The power train assembly may comprise an engine and a transmission of the motor vehicle attached to the drive train support. The step of attaching the drive train assembly to the bulkhead may comprise attaching the drive train support to the bulkhead at the attachment mounts such that the power train assembly is cantilevered from the drive train support and bulkhead. The power train support may comprise a pair of support members each having a top end and a bottom end and a cross member connecting the top ends of the support members. The method may further comprise the step of attaching a steering gear of the motor vehicle to the bottom ends of the support members to interconnect the support members. The drive train assembly may further comprise a brake and suspension assembly for each front wheel of the motor vehicle. Further, the method may comprise the step of attaching the brake and suspension assemblies to the support members, respectively.
The crash energy absorption assembly may comprise an elongated bumper beam, a pair of brackets attached to the bumper beam, and a pair of tubes each having a first end and a second end. The first ends of the tubes may be supported by the brackets. The step of attaching the crash energy absorption assembly to the bulkhead may comprise attaching the second ends of the tubes to attachment mounts preferably located on the first side of the bulkhead.
The apron assembly may be partially supported in the vertical direction by the crash energy absorption module. The apron assembly may comprise an apron member and at least one engine accessory of the motor vehicle attached to the apron member. The method may further comprise the step of attaching the at least one engine accessory of the motor vehicle to the apron member. The at least one engine accessory may be a radiator and cooling fan assembly, an air conditioning condenser, a transmission oil cooler, and/or a battery. Other possible engine accessories include fluid reservoirs for the radiator and cooling assembly, windshield wiper fluid etc. The apron member may be substantially C-shaped and have a depending front portion. The apron assembly may further comprise a substantially C-shaped apron rail. The method may comprise the step of attaching the apron rail to a top end of the apron member. The ends of the apron rail may be configured for connection to the bulkhead at the attachment mounts. The step of attaching the apron assembly to the bulkhead may comprise attaching the ends of the apron rail to the bulkhead at the attachment mounts. Furthermore, the method may comprise the steps of attaching one or more fenders of the motor vehicle to the apron rail, and attaching headlights of the motor vehicle to the front portion of the apron member.
Further details and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the drawings, wherein like parts are designated with like reference numerals throughout.